U.S. military forces in Afghanistan will no longer release data on the precise (or estimated) number of enemy troops killed in action against American forces. The previous practices of releasing this data was in contrast to the policy in Iraq. There, the U.S. deliberately stayed away from the enemy "body count" that was such a feature of the Vietnam war. But the American military did keep count, they just kept the numbers secret. Reporters kept trying to gain access to those numbers, and some of them were finally released two years ago. From 2003-7, U.S. forces killed about 20,000 enemy fighters. There's a certain amount of estimate in that, as many were killed at a distance (by smart bombs or missiles) and many bodies were blown to pieces or buried. However, data on enemy deaths is only one of dozens of things the military measures to determine how well they are doing in a combat zone. Most of those "metrics" are kept secret until long after the war ends.
In Afghanistan, the U.S. never released complete figures of enemy deaths, but often did for individual battles, or longer term operations. But now, the new policy will play down the deaths of Afghans (friendly and hostile), and instead emphasize economic aid and its impact on Afghans.
There was some talk of releasing data in which tribes and clans were pro-American, and to what extent, but it was decided that this data would be too complex for the media to handle (and most civilians to understand.) The military maintains large databases of data on who is doing what in Iraq and Afghanistan, and most of it is classified. That's because, if the enemy had knowledge of some of this data, they would know what we don't know about them, or even be able to figure out how we collected the data, or which locals helped out.